1. Field of the Invention
The invention relates to a glass sheet provided with metal mounting means attached to its border by adhesive bonding. In particular, the present invention may be used in an automobile where the glass sheet has edge strips which are adhesively bonded thereto and which are used for holding and guiding the glass sheet in the body of the automobile. The more particular example of such a sheet is a sliding glass sheet for the window in a door of a vehicle.
2. Description of the Prior Art
There is an increasing trend toward the reduction of aerodynamic drag of automobiles. For this purpose, it is known to mount the automobile glass, particularly the lateral windows, in the body of the vehicle such that the exterior surface of the sheet is completely flush with the automobile body. As a consequence, it is no longer possible to hold the sheet at its edge surface in metal U-shape strips, which yield undesirable protuberances which increase aerodynamic drag. Instead, use is made of systems, for mounting the glass sheet in the body, which do not yield protuberances at the outer surface of the glass sheet. Among the possible systems, there has been devised a system of attachment by adhesive bonding, whereby all the metal parts necessary for proper operation of the glass element (e.g., profiled pieces for holding, guiding, etc.) are adhesively bonded directly to the surface of the glass facing the interior of the vehicle.
These are considerable problems associated with achieving a durable adhesive bond between a glass sheet and metal edge-strips. One difficulty frequently encountered is that, as a general rule, adhesive materials utilized for this purpose have a very different adhesion to the metal surface on the one hand and the glass surface on the other. Thus there are adhesives which are applied over an adhesive primer and have very strong adhesion to glass, while there are other adhesives which adhere extremely well to the metals employed. However, thus far there are no adhesives which are known to be ideally appropriate for this type of application, i.e., which adhere extremely strongly to both glass and metal surfaces.
With the above-mentioned motivation, it has been previously proposed (see, e.g., German Pat. No. 2,371,100) to coat the metal holding elements, which are to be adhesively bonded to the surface of the glass, with enamel or varnish. This will confer properties on the metal surface comparable to those of a glass surface. Than one may employ adhesives which have particularly good adhesion to glass.